Enriched and depleted characters of the Amnay Ophiolite upper crustal section and the regionally heterogeneous nature of the South China Sea mantle

Issue Date

3-2013

Abstract

The volcanic section of the Middle Oligocene Amnay Ophiolite in Mindoro, Philippines has previously been shown to be of normalmid-oceanic ridge basalt (NMORB) composition. Here we report for the first time an enriched mantle component that is additionally recorded in this crustal section. New whole rock major and trace element data are presented for nine mafic volcanic rocks from a section of the ophiolite that has not been previously examined. These moderately evolved tholeiitic basalts were found to have resulted from the bulk mixing of ∼10% ocean island basalt components with depleted mantle. Drawing together various geochemical characteristics reported for different rock suites taken as representatives of the South China Sea crust, including the enriched MORB (EMORB) and NMORB of the East Taiwan Ophiolite, the NMORB from previous studies of the Amnay Ophiolite and the younger ocean floor eruptives of the Scarborough Seamount-Reed Bank region, a veined mantle model is proposed for the South China Sea mantle. The NMORB magmatic products are suggested to have been derived from the more depleted portions of the mantle whereas the ocean island basalt (OIB) and EMORB-type materials from the mixing of depleted and veined/enriched mantle regions. © 2012 Elsevier Ltd.

Source or Periodical Title

Journal of Asian Earth Sciences

ISSN

1367-9120

Volume

65

Page

107-117

Document Type

Article

Physical Description

illustrations, tables, graphs

Language

English

Subject

Amnay Ophiolite, Enriched mid-oceanic ridge basalts, Mantle source heterogeneity, South China Sea mantle

Identifier

doi:10.1016/j.jseaes.2012.09.023.

Digital Copy

yes

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